Stackable products or parts including for example trays and tote boxes or the like may be compression molded off stops out of a suitable plastic material such as fiberglass reinforced plastic. Compression molding off stops has the advantage that all of the molding pressure acts directly on the molding compound during the molding process, causing the molding compound to flow freely to better fill out the mold. However, some applications that use such compression molded stackable products in automated machinery or the like may require that the stacking height tolerances of the products be very precise, for example, on the order of ±0.004 inch. Heretofore it was not possible to hold the tolerances on thickness related details including the stacking height much higher than ±0.020 inch during compression molding of such products off stops due to the variables of charge weight and density combined with the compression molding procedure of molding off stops. Even small inconsistencies in the stacking heights of such products may be a problem especially if large numbers of the products are stacked one on top of another for handling by automated machinery.